Hypersonic aircraft to go 5 times the speed of sound

"The key thing is, hypersonics go really fast," outgoing Air Force chief scientist Mica Endsley told CNN Thursday, after announcing the target date for the new aircraft last week.

The Pentagon has been experimenting with unmanned hypersonic aircraft for years, launching them from bombers over the Pacific with limited success.

For a vehicle to be considered hypersonic, it must travel at least at Mach 5 -- five times the speed of sound, or about 3,800 mph. That's fast enough to travel across the U.S. in around 30 minutes.

Air Force Maj. Gen. Thomas Masiello last year called hypersonic technology a potential "game-changer" that will transform the nature of warfare.

China and Russia are also known to be actively building and testing hypersonic vehicles, Endsley said.

Such weapons could be launched from long distances and travel so fast they'd be virtually undetectable before reaching their targets.

Endsley said engineers have a few hurdles to overcome. Hypersonic weapons would require the development of new guidance systems and materials.

The weapons would be outfitted with "air breather" booster missiles, currently in development, that reach speeds of Mach 1 or 2 and are more efficient in their delivery than standard missiles.

After a series of failed tests, the U.S. military conducted a fourth and final test flight of the hypersonic aircraft called the X-51A Waverider in May 2013.

The tests were a part of a $300-million military project that was conceived in 2004. The first test took place in 2009. In the 2013 test, the Waverider reached Mach 5 before crashing into the ocean, as intended.

(CNN)